Small-scale miners wait for their gold to be melted into one piece before being weighed and sold at a processing plant located around 100 km (62 miles) north of the Mongolian capital city Ulan Bator in this April 5, 2012 file picture. In the last five years, dwindling legal gold supplies and a spike in black market demand from China have made work much more lucrative for Mongolia's "ninja miners" - so named because of the large green pans carried on their backs that look like turtle shells. For thousands of dirt-poor herders, the soaring prices alone are enough to justify years of harassment, abuse and hard labour. REUTERS/David Gray/Files (MONGOLIA - Tags: SOCIETY ENVIRONMENT BUSINESS EMPLOYMENT COMMODITIES) ATTENTION EDITORS PICTURE 21 OF 26 OF PACKAGE 'MONGOLIA'S GOLD RUSH.'